Cooling means for dynamometers



1954 H. BENNETT COOLING MEANS FOR DYNAMOMETERS 2 Sheets-Sheet l OrigmalFiled Feb. 19, 1941 Inventor HAROLD L. BENNETT Attorneys 1311- 1954 H.L. BENNETT COOLING MEANS FOR DYNAMOMETERS 2 Sheets-Sheet Original FiledFeb. 19, 1941 Inventor HAROLD L. BENNETT 3:: E2 0 cEwEwE m AttorneysPatented Jan. 26 1954 COOLING MEANS FOR DYNAMOMETERS Harold L. Bennett,South Bend, Ind., assignor,

by mesnc assignments, to Clayton Manufacturing Company, El Monte,Calif., a corporation Original application Febr 37,958. Divided and tuary 19, 1941, Serial No. his

application February 25, 1946, Serial No. 649,967

6 Claims.

The present invention relates to a dynamometer of the liquid resistancetype, wherein a stator tends to rotate with a rotor due to the presenceof liquid, which transmits torque from the rotor to the stator; theliquid is set into toroidal motion, absorbing the power applied to therotor, and converting it into heat.

In passing it may be pointed out that it is immaterial, in the abovearrangement, whether the rotor be the casing surrounding the stator, orthe reverse. Normally the casing is relatively stationary, and theenclosed rotor is caused to rotate by the power source to which it iscoupled.

The present invention, in one particular embodiment, relates also to apower testing machine for testing the power developed by an automobileengine, as delivered to the driving wheels of such automobile, and bythese driving wheels impressed upon wheel-cradling rolls which areoperatively connected to the dynamometer. The present invention isdivided from my Patent No. 2,428,005, issued September 30, 1947,amplifled by variant 'forms illustrating the principles involved.Whereas that patent is directed, among other things, to the relationshipof the vanes in the stator and rotor, the relative disposition of theirrims, and the expulsion of resistance water from the dynamometer casingand its recharging thereintoin brief, to the control and operation ofthe resistance water in its coupling action within the casingthisapplication is directed to the manner of dissipating the heat generatedby such operation, regardless of the specific structure by which theheat is generated in such a dynamometer, though still keeping in mindthe conditions which mustbe maintained in a dynamometer, for thedependable accuracy, reproduceability, and stability required in itsoperation.

The quite appreciable quantity of heat generated by such powerabsorption must be dissipated or removed continuously and usuallyrapidly. The small volume of resistance liquid within the dynamometercasing becomes highly heated in a short period of time, under ordinarytesting conditions. Changes of temperature of the resistance liquidcreate changes in its physical characteristics, such aschanges ofviscosity, and consequently in its ability to absorb power. Such changesmay result in a change of phase, asvfrom liquid to steam in-the case ofwater, which is the resistance liquid usually employed in suchdynamometers. The present power testing equip .ment is designed tobecapable of use at relatively low speeds but at high power, such as isdeveloped at the driving wheels of trucks under load, and under suchconditions steam is produced quickly after the start of the test. Suchchanges of phase or other physical characteristic, then,

producemarked variations in the resistance conditions, and producevariations and fluctuations in the test results, and in addition theconditions occurring during one test cannot'be controllably reproducedunder other conditions or during another test, and it follows that theresults are not capable of comparison.

Because of the collateral results discussed above, it becomes necessary,in order to obtain dependable and substantially uniform results underlike conditions, to control the temperature changes, particularly in theresistance liquid, and

to maintain such changes within narrow limits, or substantiallyconstant. This is the general object of the present invention.

It has been proposed heretofore to pass resistance Water through such adynamometer, during a test, so rapidly that it is not permitted toremain long enough that its temperature can change to a material degree,and thus to drain off and replace with cooler water that which has beenheated to some extent in its passage through the dynamometer. This isnot only a wasteful practice, but the instantaneous volume of waterwithin the dynamometer can not be accurately stabilized, and hence itsresistance varies uncontrollably; the temperature differences betweeninflowing and outfiowing water may vary over an appreciable range,because of change of temperature of incoming water, or because ofvariations in the power absorbed, hence of the heat produced; and due tosuch variations, the test results themselves will vary, and beundependable. It is evident that such a practice contributes but littleto the accuracy of the test results. Likewise, it has been proposed topass the resistance liquid primarily through a water jacket, and thenceinto the interior of the dynamometer. This too has the result ofadmitting resistance liquid at an elevated temperature, which may not bethe same under all conditions, and which may be so high under someconditions as to permit such heating of the Water (according to thesmall or large volume retained within the resistance chamber) that itspower absorption characteristics are materially different under sometest conditions than under others. This has the disadvantage, in commonwith the first expedient, that the contained volume, during fiow throughthe dynamometer, can never be kept dependably constant. In consequence,the

accuracy of this procedure leaves much to be desired.

It is a further object of the present invention to provide means forcooling the resistance liquid, and furthermore, to provide means to thisend which are separate-from the resistanceliquid itself, and. stillfurther, to provide means which are automatically responsive to increasein temperature of the resistance liquid, to effect compensating coolingof the resistance .liquid,..to the wend that its temperature is at alltimes, and by means separate from the resistancediquid, automaticallyheld to a value withinr'a'inarrow range,.or substantially constant, suchthatduringanytest operation its temperature issso nearly .the same as itwas during some other.testoperationlhalt the two results are immediatelyand directly comparable.

- It is also an object to produce the lattenresults regardless of thevolume of resistance liquid con- :tained-in the dynamometer casing,orithe-rdegree "or rapidity of its :heating and hence to permit widevariation ofthe'load-imposed upon the engine orvehicle being tested,through variation of the. volume of :resistance :liquid, without .in theleast affectingrthameans for maintaining substantially constant thetemperatureof :that'revsistance liquid.

' .;Sinc.e ,thepower absorbed by the resistance :liquid,:andconsequentlythe. heat developed thereing to-maintainthe'temperatureofthe resistance s:

water at orrbelow the desired maximum.

With the-above and similar-objects in mind, as willappear-more clearlyasthisnpecificationprog- :resses, :andfrom the claims which terminate the*same, the present invention comprises .the novel dynamometercoolingmeans, as'shownin the accompanying drawings insmore'or lessdiagramzmatic fashion and in a representative 'form, and :as ismorefully explained "in this specification anddefined by the claims at theend thereof.

The drawings either show 'a representative em- --bodiment of theinvention in a power testing machine for automobiles, or represent,diagrammatically, various wayszin which the principles of :the inventionmay be :adapted 'to .the ends in view.

Figurerl is-aplanview-With-parts brokenaway, showing :the major portionof ,a vehicle power- .testing machine whichincorporates my invention inapreferred form.

rFigure:2-.is a sideelevationofthe dynamometer,

illustrating the "various means and controls for 4 Figures 6 and 7 areside elevational views, each illustrating a diiTerent and furthermodification of the control arrangement.

The power tester illustrated in Figure 1 is of the type intended tooperate directly from the driven awheelsofian automobile or'truck, theen- .gineof which-is to be tested. z lt 'comprises a forward roll 9 anda rear roll 90, constituting apair ."spaced apart sufficiently toreceive and cradle a driving .wheel. of. .the vehicle. Roll shields 99,

which are the subject-matter of my Patent No. $2,397,461, issuedfApril2, 1946, the applicationfor which waszcopemiing herewith and dividedfrom :the sameiparerit =application, now Patent No.

2,428,005.issuedSeptember 30, 1947, permit the vehicletozbedriven'backward off such rolls. One

SUChJDalFOfQI OIIS:iS disposed at each side of the apparatus, the twopairs being spaced apart sufficientl'y'to receive-the driving wheels atthe opposite sides of the vehicle. The front rolls 9 at bothsides aresecured ito va common shaft 9|, which .in *turn constitutes or iscoupled to the 'dynamometerxshaft 8|.

Thedynamometer, in thefform illustrated, consists of an internal :rotor:80 fast upon'the shaft :8 l 'landrrotatableirelative to i2substantially stationary casing 8. Th'ercasing flf is journaled at'BZiuponthe shaft 81;:and byl'supportingmeans at 83 is connected through a'long 'fl'ever arm 84 toa pressure, sensitive device 85 upon which thearm -85 presses morezor less according to" the resistance to rotation,as'betwe'en theirotor 80 Sand 7 the casing 18. ..An.indicator:88,suitably-calibrated, measures torque or other .power factor.

:Suchtresistance torotation is developed by resistance liquid "containedWithin the :casing 8.

Radial cups slldand 18d in "the'rotor and easing,

respectively, "or other :similar arrangements, all :asxare explainedingreater detail inthe parent Patent "No. 2,428,005,11pn rotation of therotor .80 cause the contained liquid to circulate intoroidal-whirls;sand therebytto'resist rotation of the rotor, orconversely,*tend'to cause thestator casing to rotate'in'conjunction withthe rotor. The amount of liquid contained :within'the casing is variablein-a manner which'will shortly appear,

. and by this variation'the resistance'to rotation *maybe varied;

.As a convenient :means of efie'cting primary cooling of the resistanceliquid,ior more correctly, as a 'primary'means of maintainingsubstantially constant duringoperationlthe temperature of the resistanceliquid, the "casing 8' is jacketed in any suitable structuralmanner, asindicated at 86 (see Figure 3), :and'means are provided 'for circulatingthrough this jacket a coolant liquid. However, this .is onlyzonemeans'ofeffecting tempera- I ture. controly'tand :any 20131181 suitable .means'may circulating the-coolant liquid and for admitting be employedequallywell. The means for effecting. and controlling circulation of thecoolant liquid willbe explained shortly.

By reference to 'Figure 2, or, 'by'reference to the parent Patent No."$428,005, it will be seen that there is' provided at l, :subject to.icontrol by :a solenoid valve lli,'zantinlet for the resistance liquidleadingto'fthe interiornf Ith'e dynamometer casing. An outlet .fOl."thisresistance liquid is provided'at i9, subjecttoith'e controlof asolenoid valve at l8. "To'assist in'governing'to a line degree thevolume of liquid'within the casing,

means are provided for venting it. An air vent opening is "shown atZWhich may be controlled by a solenoid 'valve 28 which will be openedsimultaneously with energization of solenoid 1 valve It? to allow waterto iiow into'the dynamometer.

The air thus removed may be replaced by inflowing water withoutresistance, instead of compression of trapped air retarding its entranceand the volume of air thus compressed reducing the water capacity of theunit. Because air is allowed to escape freely through the ventingconnection, an increase in the water content of the turbine chamber maybe produced at the greatest possible rate.

To assist in decreasing the amount of water in the dynamometer rapidlywhen the outlet control solenoid valve 8 is opened, I may supplement thepumping action of the rotor, if desired, by providing a second airsolenoid valve 23 controlling the air pressure connection 29 to admitair under pressure into the central portion of the turbine chamber. Thiscompressed air will assist in driving the water out of the outlet l9.

Instead of controlling the air vent positively by a solenoid valve, thevalve 28 may be an automatic vacuum relief valve and the air ventopening control valve 28 may be merely an automatic pressure reliefvalve instead of being positively operated. In such case the lattervalve may be set to open at a pressure five or ten pounds aboveatmospheric pressure to prevent any appreciable increase in air pressurewithin the turbine chamber. Thus the dynamometer casing may becompletely filled with resistance liquid, may be completely evacuated,or may be filled or evacuated to any intermediate degree. Such controlsmay be so operated as to vary, as rapidly as may be required, theamount'of contained liquid within the dynamometer casing in the courseof any test, and while the dynamometer is running.

A thermally responsive element 3 is located either in the upper part ofthe coolant jacket 85, to which hot coolant would rise naturally, or maybe located in the turbine chamber or dynamometer casing itself, or inits circulating conduits. This thermally responsive element, as willlater be pointed out, may be connected to operate automatically any oneor more of several different controls. As shown in Figure 2 it isconnected to a solenoid valve 48 controlling the outflow of coolant at4|. Coolant is admitted at 4, and this coolant, at a rate determined bythe setting of the value at 48, circulates through the jacket 85, whichmay take the form of a cored jacket or of a coil located within theinterior of the casing 8.

The jacket 86 constitutes a means in heat exchange relationship with theresistance liquid within the dynamometer casing 3, by which the heatgenerated by the churning of the resistance liquid can be removed anddissipated. In many cases, or under many conditions, the cooling effectof this primary heat exchangenthe water jacket 86, will be sufiicient,but there will arise conditions under which the primary heat exchangerhas insufficient capacity to absorb and dissipate with suflicientrapidity all the heat which can be generated under load and during atest. I therefore provide a supplemental. heat exchanger 5, consistingof the coil 5| surrounded by the water jacket 59, the coil 5| beingconnected by the conduits H and I2 to the normal resistance liquidoutlet I9 and inlet respec tively, and the surrounding jacket 59 beingconnected by conduits 52 and 53 respectively to coolant supply and todrain 59 or other point of disposal of the coolant. A valve I3 betweenthe coil 5| and the outlet l9 typifies a means 6. of controllingcirculation of resistance liquid through the supplemental heat exchangercoil 5|, and consequently of controlling initiation and termination ofsupplemental cooling. Means other than a valve such as this, orsupplemental thereto, may be employed, as will appear later.

It may be noted at this point that, instead of testing an automobileengine indirectly through the driving wheels, the engine may beconnected directly to the shaft 9|, or otherwise directly to thedynamometer shaft 8|. In such a case it may be advantageous to employthe coolant, before it enters at 4 or at 52, or both, as a coolant forthe water jacket of the engine being tested, or the coolant after beingused in the jackets 86 or 5B, or both, may be conducted on to serve as acoolant for the engine being tested. In all cases, however, the coolantis maintained separate from the resistance liquid.

In the operation of the arrangement shown in Figure 2, a controlledquantity of resistance liquid, usually water, is admitted to theinterior of the dynamometer casing 8 by manipulation of the inlet valvesolenoid at H], and the outlet valve solenoid at |8, and, as may beneeded, by manipulation of the air vent at 2 and the air pressureconnection at 29. The supplemental heat exchanger 5 is located at asufficiently low point, with respect to the dynamometer casing 8, thatwhen the dynamometer casing is filled the supplemental heat exchangercoil 5| is like wise filled, unless for some reason it is preferred toinsert valves which will completely sever communication between thesupplemental heat exchanger and the dynamometer. Circulation will notnormally occur through the supplemental heat exchanger, however, exceptas the valve I3 is opened. The amount of resistance liquid containedwithin the dynamometer casing will be determined by the amount ofresistance it is desired to supply, as a load working against the enginewhich is being tested. As the rotor at rotates the resistance liquidwill be churned and will be given toroidal movement within thecooperating radial cups 8d and d of the stator and rotor respectively,in known manner. During such testing the amount of liquid containedwithin the dynamometer casing can be varied at will, as has already beenexplained.

The churning of the resistance liquid quickly heats it to a relativelyhigh temperature, and to maintain its temperature below the point wherethere is any danger of formation of steam, or at or near an optimumpoint where best test results are obtained, the coolant is circulatedthrough the jacket 85, entering at 4 and leaving at 4|. The controlelement at 40 controls the flow of coolant, being responsive to thethermostat at 3, which is sensitive either to the temperature of theresistance liquid directly, or indirectly to that temperature throughthe temperature of the coolant. As the temperature rises, the thermostat3 afiects the solenoid or other control element at 45, to increase therate of circulation of the coolant liquid through the jacket 85. Shouldthe temperature still continue to rise, the valve l3 may be opened moreor less, manually or by automatic means which will shortly be described,and the resistance water will commence to circulate through thesupplemental heat exchanger coil 5|. Coolant is permitted to circulatethrough the jacket 50 of the supplemental heat exchanger, entering at 52and leaving at 53, and if desired, controls may be placed on the coolantthuscirculated' through the supplemenroove/ass 'ta-l heater-tofcontrol"iterate oi clrculatiomor the circulation rate-of-theresistance liquid through the supplementafheat"exchanger'coil"5| may be'controlledby the valve 13. Eithe'r or-both such controls may beautomaticfandcontrolledby the temperature responsive element 3, or maybe manual.

In Figure 4 is *illustrated *an arrangement wherein the thermallyresponsive'e1ement'3 controls thecirculation of coolant-first attheoutlet 4 i and thereafter at theoutlet' 53. The thermallyrespcn'siveelementt,inthis instance, affects the temperature responsive oontrolelement, such as '6 which is diagrammatically illustrated in Figure 5.When thehynzirno'meter temperature reaches a given point the'latterelements expanding liquid above a diaphragmWZ closes, a switch 69thereby energizing 'the solenoid it to'open the valve at M, and ifthetemperature continues to rise-further eXpans'ion above' the diaphragm$2"closes, thestvit'ch fii energizing asolenoid 54controllingavalv'fifiin the outlet 53, In this instancathevalveIS'ina'ybe omitted or may be controlled manually or 'autom'ati'cally, asindicated by the broken lines illustrating control connectionst'o valve13in Figur'e' l. V

V In Figure"6, the thermally responsive element 3 operates onth'e valve1311 through a solenoid or similar'ele'rnent 1'5 to 'efi'ect'circulationof resistance liquid "through thesupplernental heat exchangerwheneven'no'rm'al cooling by means of the jacket fit proves'insufiicient to cool the dynamoine't'er adequately. ln 'thi instanceit'rnay be assumed that circulation through the supple-,mentalheat'ekchangei' by way'of theinletfiz and outlet 53,is"'continuous,- although itmay be con trolled 'in any in'ariner'such'ashas already been suggested.

In Figure '7 the automatic 'control'element All has been "omittedfromthe coolant outlet from the jacket 85, and "the eoolant is intended'to circulate 'freely from the inle't'fithroug h the jacket 86 and fromthe ouuet'at 4i, *and'the thermally re'sponsiveeleinent3'in"this"instance controls a solenoid or the like at 55 controlling thecoolant inlet Valli/e 51 in th'e'line Site the 'supplen'iental heateiichange'rt. In'otner words, the thermally responsive element controlscooling within the supplemental heat "exchanger rather thancirculatio'nwithin the'jacketilfi itself. 7

It 'is obvious that there might be many other arrangements in which athermally responsive element would accomplish control of circulation ofcoolant 'or "of 'theu'esistance liquid, or both. The principlei'nvolvedin all "suchcases is that the temperature of the resistance liquid is socontrolled that it may be maintained below a given maximum, onwithin "anarrow range, at such temperature as will "afford the best resultsduring a test, and 'at sucna'temperatur as can be reproduce'dandmaintained during all tests, so that't'ests made'at onetime are directlycomarable with tests made at another time.

The possibility of employing a refrigerant as the coolant whichcirculates through th jacket S G should notbe overlooked. In such casemeans may be provided to regulate 'thep-eriod and rate of circulation ofsuch refrigerant, corresponding tity o f resistance' liquid therein,during operation,"-mans 'inh eat' exchange relationship to saidresistanceliquid *to coolit; means automatically 8 opera-bio in responseto =i1iorea'se temper ature orthe "resistance' liquidtc vary"compensativel'y the heat exchange rate of said heatexchange means, tocool the resi'sta-nce liquid, and thereby automatically to maintain theresistance liquid at a substantially constant temperature duringoperation, supplemental heat exchange means in 7 heat exchangerela'tionshi'p'to said resistance liquid, operable to cool it butnormally inoperative, and means automatically operable in response to anincrease in temperature of the resistance liquid'to a"giventeinpei'ature'to effect operation of said supplemental heatexchange mean for cooling said resistance liquidfso long as thetemperatureof theresistance liquid remains elevated above such giventemperature.

2.'In a 'dynainometer "of the' liquid resistance type, anexter'nalclosed circuit circulating path to remove resistance liquid from saiddynamometer a'ndto return it thereto, mean to supply a resistance liquidto said dynamometer and to said external' 'ciroulating -path and toremove such liquid therefrom, -'to"-ma'intain any desired quantity fofresistance liquid within the dynarr'i'ornete'r, a firstrc'ooling meansin direct heat exchangerelation to the resistance liquid contained insaid dynarnometer, a second cooling means in direct heatexchangerelationto the resista'n'ce liquid "circulating throughsaid external path, "andmeans-operableautomatically in accordance with the temperatureof theresistance liquid, under quad, "to vary compensatively the coolingeffect of said first'cdoli'ng means, tending-to'inaintain constant thetemperature of said resistanceliquidf-and"further"means operableautornatically uponeievauon-pr resistance liquid temperature above agiven 'value' to-vary compensatively the *cooun euector-said secondcooling'in'ea'ns. v 7

3. A torque absorption device comprising a jacketedstatoroasi'n'g'ha'ving 'v'a'nes therein and containing resistanceliquid, "a rotor in said stator and having vanes cooperatin with saidstator vanes to churn theresis'tance liquid for absorbing power, anexternal heat ir'changer including a resistance liquid conduit connectedto said casing for reception "of resistance liquid there from and returnthereto, and "including a separate coolant conduit, in heat exchangerelation to said -resistancef liquid conduit, first coolant supply meansoperable to supply coolant to said stator'jacketjrneans-bperable tocontrol said first coolant supply rneansfse'cond coolant supply meansoperable to supply "coolant to the heat '-exchangers*coolant conduit,means operableto control *said second'coolant supply means,temperature-sensitive means operable to sense changes of tem'p'eratureof the resistance liquid, and "means controlled by saidtemperaturesensitive ineans, operatively connected to at least one ofsaid coolant supply control means, and operable automatically inresponse'to variations in the temperature of the resistance liquid toregulate compensatively the supply of coolant eite'cte'd 'by saidcoolant supply control 'means to which'it is" onnedt'eldT'tom-aintainthe resist- 1anoe liquid at substantially constant temperaure.

4. The torque, absorption "device defined in claim 3, 'th'e ineans'controlled by the temperature sensitive means beingoperatively connectedto both coolant supply control means "and operable automatically 'inrespbnseto variations in the temperature of the -resistance liquid toregulate c'ompensatively *the su-pply of coolant effected by the twocoolant supply control means to maintain the resistance liquid atsubstantially constant temperature.

5. A dynamometer of the liquid resistance type, comprising a casingdefining a space containing a resistance liquid, a conduit disposedexternally of said casing, connected to the interior of said casing andforming therewith a closed circuit for removal or resistance liquid fromand return to said casing, valve means operable to control circulationof resistance liquid through said conduit, external cooling means inheat exchange relationship with said conduit to cool the resistanceliquid flowing therethrough, means operable to supply additionalresistance liquid to said casing and conduit and to remove resistanceliquid therefrom, internal cooling means defining a coolant compartmentseparated from but in heat exchange relationship with the casing spacecontaining resistance liquid, control means operable to vary the rate offlow of coolant through the coolant compartment, means responsive tovariations in temperature of the resistance liquid within said casingspace and operatively connected to said control means, operable toregulate said control means auto matically for tending to maintainconstant the temperature of such resistance liquid, and further meanslikewise responsive to variations in temperature of the resistanceliquid in said casing space and operatively connected to said 10 valvemeans, operable to regulate said valve means automatically to vary therate of circulation of resistance liquid through said conduit forsupplemental cooling as necessary to maintain substantially constant thetemperature of the resistance liquid Within said casing space.

6. The dynamometer defined in claim 5, and means operable to controlflow of coolant through the external cooling means automatically inresponse to variations in temperature of the resistance liquid in thecasing space.

HAROLD L. BENNETT.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,743,409 Tracy Jan. 14, 1930 1,915,547 North et a1 June 27,1933 2,102,181 McCormick Dec. 14, 1937 2,116,992 Weaver May 10, 19382,144,010 Bennett Jan. 17, 1939 2,152,489 Lamb Mar. 28, 1939 2,185,491Anderson Jan. 2, 1940 2,189,189 Bennett Feb. 6, 1940 2,428,005 BennettSept. 30, 1947 2,452,550 Cline Nov. 2, 1948 FOREIGN PATENTS NumberCountry Date 11,267 Great Britain May 10, 1911 466,436 Great Britain May28, 1937

